Re: Checkpoints extreeeemely slow?

"Jonathan Lewis" <jonathan_at_jlcomp.demon.co.uk> writes:

> You don't say how big the db_block_buffer is -
> a checkpoint takes time because it is writing
> all dirty blocks to disc. For a very large
> buffer, and lots of blocks, and a single writer
> process the time required could get into this
> ballpark.
>
> At 100 blocks per second, allow 6,000 blocks
> per minute, then 15 minutes is only 90,000
> blocks. You may simply need to tune your
> db writer strategy.

Sorry I meant to include db_block_buffers. 192,000 with 8k blocks.

So are long checkpoints just a danger of having an overly large buffer cache? Would starting more db writers help keep the number of dirty blocks down? Is it preferable to start extra db writers or use db writer io slaves?

The data is in many data files (41 I think) and they're in veritas quickio files. So Oracle should be able to use asynchronous parallel writes efficiently.

-- 
greg